Syria’s antiquities chief said on Monday that his department would need five years to restore the ancient ruins of Palmyra damaged by the Islamic State jihadist group.

“If we have UNESCO’s approval, we will need five years to restore the structures damaged or destroyed by IS,” Maamoun Abdulkarim told AFP.

“We have the qualified staff, the knowledge and the research. With UNESCO’s approval, we can start the work in a year’s time.”

Abdulkarim’s remarks came after the Russian-backed Syrian army ousted IS from Palmyra on Sunday in the climax of a three-week offensive.

“Eighty percent of the ruins are in good shape,” he said.

“My expert colleagues arrive today in Palmyra. I have asked them to assess the stones and the old city. They are taking pictures of the damage and documenting everything, and then the restoration can begin.”

IS overran Palmyra in May last year, sparking global concern for the city’s spectacular ancient ruins.

The jihadists used Palmyra’s ancient theatre as a venue for public executions and also murdered the city’s 82-year-old former antiquities chief, Khaled al-Assaad.

They also destroyed the shrine of Baal Shamin.

In September, they demolished the 2,000-year-old Temple of Bel, a gem of Classical architecture, and a month later blew up the Arch of Triumph, dating from around 200 AD.

They then destroyed a dozen of the city’s best-preserved tower tombs.

Abdulkarim said a secret effort by his department had prevented the whole city from being razed.

“We were working with 45 to 50 people inside the city in order to convince Daesh, with public pressure, not to destroy everything,” Abdulkarim said, using another name for IS.

“Daesh saw that there would be a popular uprising against it if it destroyed everything. It didn’t steal and it didn’t destroy everything,” he said.

Abdulkarim said UNESCO, the UN’s culture and heritage body, would hold a meeting later this week to discuss the situation in Palmyra.